"Wayne King" <email@example.com> wrote in message <firstname.lastname@example.org>... > "alfredo " <email@example.com> wrote in message <firstname.lastname@example.org>... > > Rune Allnor <email@example.com> wrote in message <firstname.lastname@example.org>... > > > On 13 Sep, 12:10, "alfredo " <luka_...@hotmail.com> wrote: > > > > I have some problems with FIR filter,someone can help me? > > > > > > > > I write my pseudo code: > > > > > > > > clear all; > > > > Asim=[17, 18]; ?%Definisce le ampiezze > > > > Tsim=[22.5, 33.48]; ?%Definisce i periodi > > > > fase=[1.1, 2.2]; ?%Definisce le fasi > > > > p=1:2048; > > > > value=0; ?%Oscilla attorno la linea dello zero se value=0 > > > > Coseno1=0; > > > > Coseno2=0; > > > > Coseno1=Coseno1+Asim(1)*cos(2*pi*1/Tsim(1)*p+fase(1))'; > > > > Coseno2=Coseno2+Asim(2)*cos(2*pi*1/Tsim(2)*p+fase(2))'; > > > > > > > > serie12=Coseno1+Coseno2; > > > > step =0.01; > > > > > > > > serie= serie12; > > > > step=0.01; > > > > Tmin=8; > > > > Tmax=120; > > > > A=length(serie); > > > > > > > > Y=fourier(serie',Tmax,Tmin,step); ? ? ? ? ? ?%fourier trasform > > > > > > > > Ok , now how can I implement a high pass filter FIR, for cut off ?the frequency 1/ 33.48 ? > > > > > > What has all this to do with designing filters? > > > > > > Rune > > > > > > > > I try with this: > > > > d = fdesign.highpass('Fst,Fp,Ast,Ap',0.03,0.043,60,0.5,10000) ; > > Hd = design(d,'FIR'); > > smoothed_data = filter(Hd,Y); > > > > but I have some problems, I thik because I have R2007b version... > > Hi Alfredo, the filter specification objects such as fdesign.highpass were introduced in the Signal Processing Toolbox in R2009a, they are part of the Filter Design Toolbox prior to that. > In R2007b, you have a number of non-object-oriented FIR design routines available in the Signal Processing Toolbox. Take a look at firpm() for an equiripple design, fir1() for a window method FIR design, fir2() uses frequency sampling, and firls() for least-squares error minimization as examples. Post back if you have difficulty, I'm not sure you really want the filter design you have above in fdesign.highpass (or I would have given you a comparable example) because you are basically just passing everthing. Your stopband frequency is only 0.03 Hz? (you have a sampling frequency of 10 kHz specified), your passband starts at 0.043 Hz... > > Hope that helps, > wayne
thank you for this information, I try immediately these function but I can select if I want a high pass or a lowpass filter? the freq 0,03 and 0.043 ara the inverse of the period of cicles 22.5 and 33.48 ( I want to cutoff the 33.48 period cycle ), I'm not sure of f sampling becouse I work with time series .